cometic gaskets

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70wayfarer

70wayfarer

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just a couple of things i'm not clear on.
can you reuse cometic gaskets, and is copper spray ok for aluminum heads.
the reason i ask is i've made the change to hydraulic roller cam and didn't remember to clearance the pushrod bores. they are eddy rpm's. also i had coated the gaskets with copper spray. someone suggested that you don't use copper coat with ali heads.the copper coat i used was a vht product.
i have removed the heads for clearancing for pushrods and the copper coat cleaned off easily.
this is a new build.
thanks in advance for ya help.
 
I personally have used my cometic head gaskets 3 times. I was advised by local shop to keep gaskets matched to side they were removed from,clean them with fresh mineral spirits each time, use air gun to blow off any residual and let dry. Before reapplication spray generously with copper gasket sealant. This has been done on my eddy headed 340 with no problems. This was done to have heads milled, and also had to pull them again for push rod clearance when I went to roller cam. I wont try a 4th time but have had perfect results with 3. Hope this helps.
 
340Truck said:
I personally have used my cometic head gaskets 3 times. I was advised by local shop to keep gaskets matched to side they were removed from,clean them with fresh mineral spirits each time, use air gun to blow off any residual and let dry. Before reapplication spray generously with copper gasket sealant. This has been done on my eddy headed 340 with no problems. This was done to have heads milled, and also had to pull them again for push rod clearance when I went to roller cam. I wont try a 4th time but have had perfect results with 3. Hope this helps.
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read they could be used 3 times, hope it`s 4 !
 
Cometic does not recommend using any other sealants, but then again, they don't go on to discuss gasket reuse in their online technical notes. My only hesitation on using copper on AL is that there might be a tendency towards corrosion between the 2 metals around the coolant ports, due to electrolysis. But the copper sprays have a lot of 'goo' in them that might prevent this.
 
nm9stheham said:
Cometic does not recommend using any other sealants, but then again, they don't go on to discuss gasket reuse in their online technical notes. My only hesitation on using copper on AL is that there might be a tendency towards corrosion between the 2 metals around the coolant ports, due to electrolysis. But the copper sprays have a lot of 'goo' in them that might prevent this.
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the electrolysis thing is what was said to me, but it seems most guys with alu heads are using copper coat.
 
Straight copper and aluminum react pretty quickly and strongly, even with just atmospheric moisture. It should only take place in the presence of moisture and other electrolytes. If there is good coolant kept in, and it's changed every few years, then I would think that the anti-corrosive additives in the anti-freeze ought to keep it from happening.
 
I had cometic gaskets make me .100 thick head gaskets. I had j heads milled down to 59 cc for my race motors. I wanted to use those heads on a street motor I put together. So I had cometic make me the head gaskets to get my compression ratio to 9.5 to 1. I have reused the gaskets 3 times with no sprays or adhesion and no leaks.
 
I will defer to The Honored Posters, before I lend My limited experience.
 
mech1nxh said:
I will defer to The Honored Posters, before I lend My limited experience.
Click to expand...

don't hold back....

anywho, consensus leans toward using copper coat is ok. i have not used cometics with aluminum heads before, only iron heads.
 
70wayfarer said:
don't hold back....
Click to expand...
OK then :) lost the Engine, won the race...
attachment.php


70wayfarer said:
anywho, consensus leans toward using copper coat is ok. i have not used cometics with aluminum heads before, only iron heads.
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P.s, 4x reuse of Cometic MLS gasket @ 28 # boost --- tune failed---
The head gasket is still in use on a 38# boost short fuse 'psycho' build .

???Copper coat ??? LMFAO, ( WITH RESPECTS) why???
---Ever torn down a factory build & seen 'sealant' around a fire ring ---

I now relinquish the floor To My Most Honored Constituents ;)
 
mech1nxh said:
OK then :) lost the Engine, won the race...
attachment.php




P.s, 4x reuse of Cometic MLS gasket @ 28 # boost --- tune failed---
The head gasket is still in use on a 38# boost short fuse 'psycho' build .

???Copper coat ??? LMFAO, ( WITH RESPECTS) why???
---Ever torn down a factory build & seen 'sealant' around a fire ring ---

I now relinquish the floor To My Most Honored Constituents ;)
Click to expand...

Norm,most of the 30+ pound boosted Ford Mod motor guys,use these multiple overhauls,and passes.. That's was the skinny on Ford /Turbostang's sites... However,appropriate fasteners(read : head studs,and the tensile strength gig,come into effect..) I won't plug a unfusible link,into a bomb.. I simply cannot afford high maintenance, & repair.. However,they are outstanding, they do need a certain maintenance, block/head surface prep,. They are worth every penny,in certain situations. ( I have read this,seen them installed on builds I have been involved with..Very minimum maintenance...Chevy exp..)
 
we used copper coat on our W5 build the second time we had it apart. we had some coolant weepage external the first time we used them. Coated never had any leakage.
 
Copper spray has very little copper in it. As noted, unless it's "getting wet" you won't have any trouble. Cometics can be reused but you do need to be careful about keeping the surfaces clean and flat.
 
Abodybomber said:
Norm,most of the 30+ pound boosted Ford Mod motor guys,use these multiple overhauls,and passes.. That's was the skinny on Ford /Turbostang's sites... However,appropriate fasteners(read : head studs,and the tensile strength gig,come into effect..) I won't plug a unfusible link,into a bomb.. I simply cannot afford high maintenance, & repair.. However,they are outstanding, they do need a certain maintenance, block/head surface prep,. They are worth every penny,in certain situations. ( I have read this,seen them installed on builds I have been involved with..Very minimum maintenance...Chevy exp..)
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Always a pleasure Mr Tim San :D.
Honored Posters, lets think on this for a bit.
Cometic's design uses 3 layers in the gasket 'proper'.(up to 5 or 6 in some S/O Nitro apps)

Back on topic, for the purposes of the O/P,s topic
Surface (head & block) finish is paramount & then fastener 'evolved tech'.

So, rewind---
We have 6 'layers' of seal surface. (dry)
on the gasket & then 2 more ---head & block = 8 total :)

& Back on topic, why exactly would Anyone add a lubricant (copper)
to a properly surface finished head & block ???

Honored Posters Please do not take My humble thoughts as a slight
to Ya'lls wisdom . Thx !!!
 
I'd say you get lucky if their reusable or not. I put a set on my 408 when I first built it. At 5000 miles I pulled the heads off because the guides were leaking down bad and much of the coating peeled off and stayed on the block and heads.
 
mech1nxh said:
Always a pleasure Mr Tim San :D.
Honored Posters, lets think on this for a bit.
Cometic's design uses 3 layers in the gasket 'proper'.(up to 5 or 6 in some S/O Nitro apps)

Back on topic, for the purposes of the O/P,s topic
Surface (head & block) finish is paramount & then fastener 'evolved tech'.

So, rewind---
We have 6 'layers' of seal surface. (dry)
on the gasket & then 2 more ---head & block = 8 total :)

& Back on topic, why exactly would Anyone add a lubricant (copper)
to a properly surface finished head & block ???

Honored Posters Please do not take My humble thoughts as a slight
to Ya'lls wisdom . Thx !!!
Click to expand...

was hoping you would chime in mech1nxh......was told when i started my turbo build to use cometic gaskets to contain the added compression of boost. was also told to fit them dry with a thin smear of sealer around the water galleries only.
i am rebuilding after det ate #8 piston, iron heads, blow through carb. have now invested in eddy heads, efi, roller cam $$$$$$$$$
 
70wayfarer said:
was hoping you would chime in mech1nxh......was told when i started my turbo build to use cometic gaskets to contain the added compression of boost. was also told to fit them dry with a thin smear of sealer around the water galleries only.
i am rebuilding after det ate #8 piston, iron heads, blow through carb. have now invested in eddy heads, efi, roller cam $$$$$$$$$
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Always a Pleasure 70wayfarer !!! I am not a guru of builds, rather
just a Psycho Gearhead that has learned from experience !!!
(read ruined more Mopar race parts than The good Lord should Allow) LOL !!!

:) with respects , ???? sealant ??? = lack of proper surface prep !!!

??? who are these people that are that are giving You ??? advise ???
AHAHAHAHAH, BUHAHAHAHAHAHA,
Shoot Me a P/M & We'll get onto some 'quiet tire f'n frying som beetch ground bound Halley's comet build options !!!!

Oh, get out Your Mic of choice & measure the ' fire ring' on a ... mmmm...
competitive gasket !!! Again, I am no guru :) . --- bet ya --- You find
> than .030 on the Cometic. !!!

The real 'beauty' of the Cometic Group (et al sp?) is their consummate
engineering genius !!! them thar boys figured out how to keep a fire ring
stable under 'literally' stupid amounts of boost !!!

Or 'heat saturation'(read 'block wiggle lol' )in an 9-10 k rpm Nascar build.

Apologies Honored Posters !!!
Got a bit 'wound up' --- its a gearhead thing---
But then its safe here at FABO

Edit,
I am gonna fly to Kiwi land & steal your Ute 70wayfarer....
ahahahahaha, buhahahahaha,

What??? just humor ;)
 
mech1nxh, as far as I can tell might be the only one with "the skinny" on Cometic.
The Powersports industry (motorcycle,ATV, snowmobile, etc.) has been using MLS type gaskets for years. They are not something new. They are not considered re-usable.
As Fishy mentioned, often times the coating of the gasket sticks and peels upon disassembly.
If you need sealants with them, it's because your surfaces are not up to the proper standard/finish quality to run them.
It amazes me how many people want to do some "redneck/home re-engineering" of MLS gaskets...(one guy here mentioned separating the layers and copper spraying all layers)
MLS type gaskets are great, and have their place here in our builds.
They also have to be planned for in our machining.
And of course, this will come up again... over and over...
 
I never use copper spray and I never reuse gaskets, why take the chance? new gaskets are cheap, for 75 bucks per head gasket I wouldn't even bother to chance it, I throw them on the scrap pile, and I had my heads off 4 time last summer
 
71beater said:
mech1nxh, as far as I can tell might be the only one with "the skinny" on Cometic.
The Powersports industry (motorcycle,ATV, snowmobile, etc.) has been using MLS type gaskets for years. They are not something new. They are not considered re-usable.
Click to expand...
With all due respects, #1 Son worked for Polaris for years, & placed 7 in the '99
World Finals at Havasu (Novice 785 S/S Class), so I guess now theres two of us
with the 'skinny'... We reused a bunch of the Cometics ...

71beater said:
If you need sealants with them, it's because your surfaces are not up to the proper standard/finish quality to run them.
Click to expand...
Agreed
71beater said:
It amazes me how many people want to do some "redneck/home re-engineering" of MLS gaskets...(one guy here mentioned separating the layers and copper spraying all layers)
MLS type gaskets are great, and have their place here in our builds.
They also have to be planned for in our machining.
Click to expand...
Agreed x2
71beater said:
And of course, this will come up again... over and over...
Click to expand...
Agreed x3

P.s, krazycuda,
I know what Cometic gaskets look like, could You post a pic
of the 'dead soft copper' gaskets (with copper sealant) You
use on Your builds ?
I am not familiar with those.
Thx.
 
70wayfarer said:
the electrolysis thing is what was said to me, but it seems most guys with alu heads are using copper coat.
Click to expand...

Aluminum heads and standard Fel-Pro gaskets @ 11-1 ratio. Never an issue.

skrews said:
Use Hylomar spray instead of copper coat.
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That's the stuff!

torkflight said:
I never use copper spray and I never reuse gaskets, why take the chance? new gaskets are cheap, for 75 bucks per head gasket I wouldn't even bother to chance it, I throw them on the scrap pile, and I had my heads off 4 time last summer
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$75 can be quite a lot when changing multiple times a year. I have, but don't suggest, reusing head gaskets. Most use I have gotten was 3 time head off and on the engine with the same head gasket.
 
my heads and decks have been machined for cometics. will try and sorse some hylomar, otherwise will fit with no coating.

cheers for the input guys.
 
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